But now Northern Ireland's first roof garden restaurant must dismantle its eye-catching external décor that cost £20,000 – or face a substantial fine.

AM:PM and its Cabaret Supper Club have launched a petition on social media after the Department of the Environment (DoE) issued its decision, saying the "size and positioning" of banners and awnings were "unacceptable".

Eamon McCusker (42), who owns the entertainment complex on Upper Arthur Street in Belfast, has branded the ruling ridiculous. However, the DoE has told the Belfast Telegraph that planning officials will meet Mr McCusker on Monday to discuss the situation.

"Three years ago we carried out major renovations here to attract customers because so many businesses were going bust," said Mr McCusker.

"We put a lot of investment into expanding the restaurant downstairs, we created a brand new concept called the Cabaret Supper Club on the first floor, and then we created Ireland's first roof garden restaurant on the top floor.

"This isn't an attractive part of the city so we also decided to do something different with respect of the front of the building in order to reflect the ambience and the decor internally, just to give people a snapshot of what exactly the whole place is about.

"Outside the building we invested in 1920s-style awnings, which are stunning, and we imported artificial green hedging to cover the stark horrible red brick that was on the building.

"Then we put fairy lights all through the hedging in front of the building."

The row – which erupted after the proprietor of the premises applied for retrospective planning permission – comes at a time when the Department for Social Development (DSD) is facing criticism for the huge amounts it has spent on fake shop fronts for derelict retail units.

Mr McCusker said he was shocked the renovations have been criticised for conservation reasons.

"We've been told by the DoE to take down everything that we've done – the awnings, the lights," he said. "I can't believe it. It doesn't seem fair to be punishing a business that is trying to help itself in this extremely difficult trading climate."

A DoE spokeswoman said the department acknowledged the contribution businesses made to our local economy but stressed that this was a conservation area in the heart of Belfast.

"We need planning rules otherwise buildings, extensions to buildings and advertisements of all shapes and sizes, which may not be in keeping with the conservation area, could appear," she said. "These enforcement notices did not come out of the blue. Two warning letters were issued to the manager of the premises, which were ignored.

"The minister has asked planning officials to meet with the applicant who has applied for retrospective planning permission. They have done that, they will continue to do that in order to try and resolve outstanding issues. The enforcement proceedings will not be pursued until the planning issue is resolved."

Other pubs to fall foul of planning red tape

Sunflower bar, Union Street

Belfast's Sunflower bar was told by the Department for Regional Development to remove the security cage at its front door, although it is still there. Erected 25 years ago, it was originally a security measure that enabled staff to identify people before they entered the bar. A relic of the Troubles, it is now a quirky photo opportunity for visitors and locals alike.

The Apartment, Donegall Square West

The Apartment in Belfast was threatened with a £2,500 fine for trying to entice customers in with a meal deal.

It was told by the DoE to remove a large window banner in January 2013. Measuring around 6ft in height and up to 15ft wide, the sign in question was positioned above the front doors of the Donegall Square West bar, which is situated opposite City Hall.

The Hudson bar, Gresham Street

The Hudson bar on Gresham Street was told to remove an A–Board advertising its wares from North Street because it was deemed too far away from its premises – despite its purpose being to let customers know of the bar's existence.

The situation was only resolved when the owner agreed to put it on Royal Avenue at the entrance of the pub's beer garden.